/Engine/Source/Runtime/TypedElementRuntime/Public/Elements/Interfaces/TypedElementSelectionInterface.h
Test to see whether selection modifiers (Ctrl or Shift) are allowed while selecting this element.
virtual bool AllowSelectionModifiers ( const [FTypedElementHandle](API\Runtime\TypedElementFramework\Elements\Framework\FTypedElementHandle) & InElementHandle, const FTypedElementListConstPtr & InSelectionSet )